Germany has awarded medals of honor to a French couple who spent decades bringing Nazi war criminals to justice — sometimes by unconventional means.

Jewish lawyer Serge Klarsfeld and his German-born wife Beate received the Order of Merit at the German embassy in Paris on Monday.

The couple spent decades hunting down Nazis who had gone into hiding after World War II, including Klaus Barbie. The notorious "Butcher of Lyon" was eventually extradited from Bolivia in 1983.

The Klarsfelds' work often embarrassed governments that had failed to apprehend former Nazis and, in Germany's case, allowed them to rise to high office.

In 1968, Beate Klarsfeld famously slapped then-German Chancellor Kurt Kiesinger at a political rally after denouncing his pre-war membership of the Nazi party.